KnowRoaming

If you spend a lot of time traveling internationally, you know what a pain it can be to maintain a phone that works all over the world, without going broke doing it. KnowRoaming ($35) is an intelligent sticker and an iOS or Android app combination that makes traveling with your phone easier and cheaper. Just apply the sticker to the front of your SIM card, and it takes care of the rest — staying off until you need it, and switching on to prevent roaming charges internationally. The accompanying app lets you monitor your usage, while finding carriers internationally and allowing you to top up on minutes that never expire.

Site Meter